The role of subcellular organelles in hormone secretion : The interactions of calcium, vitamin A, vinblastine, and cytochalasin B in PTH secretion

To determine the role of subcellular organelles in hormone secretion, we studied the interaction of low calcium concentration (low Ca), retinol (vitamin A, vit A), vinblastine (VB), and cytochalasin B (CB) in parathyroid hormone (PTH) secretion. Bovine parathyroid tissue pieces were incubated in media containing the above agents. Vit A stimulated PTH release to a mean of 170% of control. This effect of vit A was diminished when tissues were simultaneously stimulated with low Ca and, furthermore, absent when tissues were pre-incubated in low Ca.VB had no effect on low Ca-stimulated secretion, but did inhibit vit A-induced secretion in the presence of low Ca.CB stimulated PTH secretion to a mean of 150% of control during the second and third hours of incubation. CB had at least an additive effect with low Ca in stimulating PTH secretion, with a more prompt and greater response than seen in normal calcium. VB did not inhibit the acute effect of CB on secretion in normal calcium media, but did inhibit CB-induced secretion during the third hour of incubation.None of the agents stimulated the release of lysosomal cathepsin D, and vit A and CB did not stimulate the release of LDH.Our results suggest that; (1) vit A and low Ca stimulate PTH secretion through a common pathway involving the cell membrane; (2) CB stimulates PTH secretion through a separate effect on the cell membrane or submembrane microfilaments, which normally retards secretion of PTH; and (3) microtubular proteins may facilitate basal secretion of PTH, but are not involved in low Ca-stimulated secretion of PTH.     

Characteristics of the induction of aldehyde dehydrogenase in rat liver

The activity of rat liver supernatant aldehyde dehydrogenase is increased by phenobarbital treatment in one selected strain (RR) but not in another strain (rr) of animals derived from randomally bred populations (Deitrich, Collins, and Erwin (1972) J. Biol. Chem., 247, 7232). Before 14 days of age, increased enzyme activity after phenobarbital treatment is minimal but between 30 and 60 days of age there is a maximal increase in activity after phenobarbital treatment. Using animals of this age, it was shown that both cycloheximide and actinomycin D block this response to phenobarbital. Phenobarbital treatment decreases heat stability of crude preparations of the enzyme from RR rats, but increases heat stability of the enzyme from rr animals.     

Isolation and characterization of a virulent bacteriophage from Staphylococcus carnosus

Abstract A virulent bacteriophage, øSK311, was isolated from Staphylococcus carnosus , an organism used as a starter culture for the production of dry sausage. Electron microscopic studies revealed that this bacteriophage showed some morphological similarities with the Escherichia coli phages T4 and λ. The host range of øSK311 extends over 9 different staphylococcal species. A phage-resistant mutant of S. carnosus could be isolated. Cells of this mutant exhibited a capsule-like structure. The DNA of øSK311 possesses a G + C content of 31.4 mol% and appears to be highly modified.     

Microbial diversity of intestinal contents and mucus in rainbow trout (Oncorhynchus mykiss)

AIMS: The aim of this study was to understand the microbial community of intestinal contents and mucosal layer in the intestine of rainbow trout by means of culture-dependent conventional and independent molecular techniques. METHODS AND RESULTS: Forty-one culturable microbial phylotypes, and 39 sequences from 16S rRNA and two from 18S rRNA genes, were retrieved. Aeromonadaceae, Enterobacteriaceae and Pseudomonadaceae representatives were the dominant cultured bacteria. Genomic DNA isolated from intestinal contents and mucus was used to generate 104 random clones, which were grouped into 32 phylotypes at 99% minimum similarity, most of which were affiliated with Proteobacteria (>70% of the total). However, unlike library C (intestinal contents), the phyla Bacteroidetes and Fusobacteria were not found in intestinal mucus (library M), indicating that the microbiota in the gut mucus was different from that of the intestinal contents. Twelve sequences were retrieved from denaturing gradient gel electrophoresis analysis, and dominant bands were mostly related to Clostridium. CONCLUSIONS: Many novel sequences that have not been previously recognized as part of the intestinal flora of rainbow trout were retrieved. SIGNIFICANCE AND IMPACT OF THE STUDY: The fish gut harbours a larger bacterial diversity than previously recognized, and the diversity of gut mucus is different from that of intestinal contents.     

A novel homozygous 10 nucleotide deletion in BBS10 causes Bardet–Biedl syndrome in a Pakistani family

Bardet–Biedl Syndrome is a multisystem autosomal recessive disorder characterized by central obesity, polydactyly, hypogonadism, learning difficulties, rod-cone dystrophy and renal dysplasia. Bardet–Biedl Syndrome has a prevalence rate ranging from 1 in 100,000 to 1 in 160,000 births although there are communities where Bardet–Biedl Syndrome is found at a higher frequency due to consanguinity. We report here a Pakistani consanguineous family with two affected sons with typical clinical features of Bardet–Biedl Syndrome, in addition to abnormal liver functioning and bilateral basal ganglia calcification, the latter feature being typical of Fahr's disease. Homozygous regions obtained from SNP array depicted three known genes BBS10, BBS14 and BBS2. Bidirectional sequencing of all coding exons by traditional sequencing of all these three genes showed a homozygous deletion of 10 nucleotides (c.1958_1967del), in BBS10 in both affected brothers. The segregation analysis revealed that the parents, paternal grandfather, maternal grandmother and an unaffected sister were heterozygous for the deletion. Such a large deletion in BBS10 has not been reported previously in any population and is likely to be contributing to the phenotype of Bardet–Biedl Syndrome in this family.     

DNA methylation changes in photoperiod-thermo-sensitive male sterile rice PA64S under two different conditions

Epigenetic modification can occur at a high frequency in crop plants and might generate phenotypic variation without changes in DNA sequences. DNA methylation is an important epigenetic modification that may contribute to environmentally-induced phenotypic variations by regulating gene expression. Rice Photoperiod-Thermo-Sensitive Genic Male Sterile (PTGMS) lines can transform from sterility to fertility under lower temperatures and short-day (SD) conditions during anther development. So far, little is known about the DNA methylation variation of PTGMS throughout the genome in rice. In this study, we investigated DNA cytosine methylation alterations in the young panicles of PTGMS line PA64S under two different conditions using methylation sensitive amplified polymorphism (MSAP) method. Compared with the DNA methylation level of PA64S under lower temperatures and SD conditions (fertility), higher methylation was observed in PA64S (sterility). The sequences of 25 differentially amplified fragments were successfully obtained and annotated. Three methylated fragments, which are homologous to D2, NAD7 and psaA, were confirmed by bisulfite sequencing and their expression levels were also evaluated by qPCR. Real time quantitative PCR analysis revealed that five of the six selected methylated genes were downregulated in PA64S (sterility). These results suggested that DNA methylation may be involved in the sterility–fertility transition of PA64S under two different environmental conditions.     

FRIL蛋白体外维持脐血造血干/祖细胞的作用及细胞周期调控基因的表达

为探讨新的豆类凝集素(Flt3 receptor-interacting lectin,FRIL)体外维持脐血CD34^ 细胞的作用以及维持过程中细胞周期调控基因HTm4及HTm4S mRNA的表达及意义,我们利用FRIL维持培养脐血CD34^ 细胞,对其增殖曲线、细胞周期及集落形成能力进行常规分析,并用半定量RT—PCR法分别测定FRIL体外维持不同时间后脐血CD34^ 细胞中周期调控基因HTm4及HTm4S mRNA的表达变化。结果显示,FRIL培养的CD34^ 造血干／祖细胞的增殖趋势平缓,整个培养期间细胞增殖倍数不超过起始的3倍：14d之前,FRIL培养细胞的高增殖潜能集落形成细胞(HPP—CFC)形成集落数与FL组无差别,其后则维持高于FL的情况。细胞周期分析则显示,在28d的培养过程内,利用FRIL培养的细胞始终有80％以上维持在G0期;而周期调控基因HTm4及HTm4S在刚分离的脐血CD34^ 细胞中的表达水平较高;但培养1d后,几乎检测不到HTm4基因的表达;培养3～14d,该基因的表达回升并持续维持在高水平。而HTm4S基因的表达在第7d达最高水平,其余时间基本呈稳定表达。转染HTm4和HTm4S,亚细胞定位结果显示HTm4主要定位于核周围,而HTm4S则定位于整个胞浆,由此可能导致它们功能的区别。以上结果提示,长期培养体现出FRIL在维持造血干／祖细胞多能性上的优势;细胞周期调控基因HTm4及其新剪接子参与了FRIL体外长期维持脐血造血干／祖细胞处于静息状态的过程。     

稻纵卷叶螟感染Wolbachia的ftsZ基因和16S rDNA基因的序列分析

Wolbachia是一类胞质遗传的内共生菌, 广泛分布于节肢动物和其他动物中, 与宿主的生殖调控密切相关。通过研究迁飞性害虫稻纵卷叶螟Cnaphalocrocis medinalis (Guenée)的Wolbachia感染情况, 为探讨Wolbachia在迁飞性昆虫中的生殖调控和传递方式等提供基础资料。本研究应用Wolbachia的ftsZ基因和16S rDNA基因的特异性引物, 通过PCR扩增的方法对我国20个地区的稻纵卷叶螟样本进行了检测。结果表明: 中国不同地区的稻纵卷叶螟感染Wolbachia的现象较为普遍, 其中浙江温州和江苏扬州样本的感染率最高（90%）; 四川雅安、 湖南长沙和天津宁河样本的感染率最低（40%）。不同地区稻纵卷叶螟的Wolbachia ftsZ基因序列完全一致, 而且不同地区的Wolbachia 16S rDNA基因序列也完全相同。此外, 稻纵卷叶螟感染的Wolbachia ftsZ基因和16S rDNA基因序列与其他物种感染的Wolbachia B群的ftsZ基因序列和16S rDNA基因序列相似性分别在99%~100%和98%~99%之间, 说明我国稻纵卷叶螟感染的Wolbachia隶属B群。研究结果表明, 稻纵卷叶螟感染的Wolbachia类型较为单一, 这也是我国有关稻纵卷叶螟内共生菌Wolbachia的首次研究报道。